In vertebrate animals, the heart is a hollow muscular organ having four pumping chambers: the left and right atria and the left and right ventricles, each provided with its own one-way outflow valve. The natural heart valves are identified as the aortic, mitral (or bicuspid), tricuspid and pulmonary valves. The valves separate the chambers of the heart, and are each mounted in an annulus therebetween. The annuluses comprise dense fibrous rings attached either directly or indirectly to the atrial and ventricular muscle fibers. The leaflets are flexible collagenous structures that are attached to and extend inward from the annuluses to meet at coapting edges. The aortic and tricuspid valves have three leaflets, while the mitral and pulmonary valves have two.
Various problems can develop with heart valves, for a number of clinical reasons. Stenosis in heart valves is a condition in which the valves do not open properly. Insufficiency is a condition which a valve does not close properly. Repair or replacement of the aortic or mitral valves are most common because they reside in the left side of the heart where pressures and stresses are the greatest. In a valve replacement operation, the damaged leaflets are excised and the annulus sculpted to receive a replacement prosthetic valve.
In many patients who suffer from valve dysfunction, surgical repair (i.e., “valvuloplasty”) is a desirable alternative to valve replacement. Remodeling of the valve annulus (i.e., “annuloplasty”) is central to many reconstructive valvuloplasty procedures. Remodeling of the valve annulus is typically accomplished by implantation of a prosthetic ring (i.e. “annuloplasty ring”) to stabilize the annulus and to correct or prevent valvular insufficiency that may result from a dysfunction of the valve annulus. Annuloplasty rings are typically constructed of a resilient core covered with a fabric sewing ring. Annuloplasty procedures are performed not only to repair damaged or diseased annuli, but also in conjunction with other procedures, such as leaflet repair.
Mitral valve regurgitation is caused by dysfunction of the mitral valve structure, or direct injury to the mitral valve leaflets. A less than perfect understanding of the disease process leading to mitral valve regurgitation complicates selection of the appropriate repair technique. Though implantation of an annuloplasty ring, typically around the posterior aspect of the mitral valve, has proven successful in a number of cases, shaping the surrounding annulus does not always lead to optimum coaptation of the leaflets.
More recently, a technique known as a “bow-tie” repair has been advocated. The bow-tie technique involves suturing the anterior and posterior leaflets together in the middle, causing blood to flow through the two side openings thus formed. This process was originally developed by Dr. Ottavio Alfieri, and involved placing the patient on extracorporeal bypass in order to access and suture the mitral valve leaflets.
A method for performing the bow-tie technique without the need for bypass has been proposed by Dr. Mehmet Oz, of Columbia University. The method and a device for performing the method are disclosed in PCT publication WO 99/00059, dated Jan. 7, 1999. In one embodiment, the device consists of a forceps-like grasper device that can be passed through a sealed aperture in the apex of the left ventricle. The two mitral valve leaflets meet and curve into the left ventricular cavity at their mating edges, and are thus easy to grasp from inside the ventricle. The mating leaflet edges are grasped from the ventricular side and held together, and various devices such as staples are utilized to fasten them together. The teeth of the grasper device are linearly slidable with respect to one another so as to align the mitral valve leaflets prior to fastening. As the procedure is done on a beating heart, and the pressures and motions within the left ventricle are severe, the procedure is thus rendered fairly skill-intensive.
There is presently a need for an improved means for performing the bow-tie technique of mitral valve repair.